COPYRIGHT AND CITATION CONSIDERATIONS FOR THIS THESIS/ DISSERTATION o Attribution — You must give appropriate credit, provide a link to the license, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use. o NonCommercial — You may not use the material for commercial purposes. o ShareAlike — If you remix, transform, or build upon the material, you must distribute your contributions under the same license as the original. How to cite this thesis Surname, Initial(s). (2012) Title of the thesis or dissertation. PhD. (Chemistry)/ M.Sc. (Physics)/ M.A. (Philosophy)/M.Com. (Finance) etc. [Unpublished]: University of Johannesburg. Retrieved from: https://ujdigispace.uj.ac.za (Accessed: Date). SEASONAL EXPOSURE IN THE FORM OF PRECIPITATION AND ITS EFFECT ON WATER QUALITY FOR THE ROODEPLAAT DAM DRAINAGE BASIN: 2000 – 2009. Nicole Janet LOMBERG Minor Dissertation submitted in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE in ENVIRONMENTAL MANAGEMENT Faculty of Science University of Johannesburg Supervisor: Prof. J.T. Harmse December 2010 ABSTRACT The main purpose of this study is to determine whether trends in rainfall patterns correlate to trends in water quality constituents for the Roodeplaat Dam Drainage Basin, thereby increasing the ‘dilution capacity’ potential of the aforementioned water system. The Roodeplaat Dam (reservoir) is a hypertrophic impoundment located approximately 20 kilometres north-east of Pretoria. The dam was originally designed for irrigational purposes and later became an important recreational site. In recent years it serves as an important source for Magalies Water, which represents a state-owned water board that currently supplies potable water to a large area north of Pretoria. The Roodeplaat Dam catchment consists of three contributing rivers to the inflow of the impoundment, namely: The Pienaars River (located in the centre of the catchment), the Edendale Spruit (east of the catchment) and the Moreleta/Hartebees Spruit (west of the catchment). There are also two Water Care Works (Zeekoegat and Baviaanspoort) within the catchment, which supplement additional inputs of treated effluent discharges to the reservoir. Temporal changes in selected physical, chemical and microbial constituents were analysed at established sampling points along each river, including a sample site located at the dam wall outlet. Such changes in water quality, in conjunction with rainfall patterns exhibited in the study area were analysed to determine whether an association exists between the two variables, and more specifically how rainfall impacts on water quality within the catchment which has a direct effect on the quality of the Roodeplaat Dam. Data for rainfall and water quality were analysed over a 10 year period, from January 1999 to December 2009. Water quality sampling results were obtained from the Department of Water Affairs. Rainfall data for the same time period in question was obtained from the South African Weather Service. Results for both variables were projected graphically and collated to determine whether rainfall trends have an impact on concentrations of water quality constituents. Constituent concentrations were also compared at each sample site. To quantitatively justify graphical results, the author preformed Pearson’s and Spearman’s correlation analysis to establish whether rainfall and water quality concentrations displayed significant associations. i Results from graphical presentations and quantitative analyses identified that a correlation does exist between rainfall and water quality constituents, whereby an increase in rainfall tends to result in a decrease of water quality constituent concentrations. Microbial constituents contrasted to physical and chemical results, and displayed a strong positive correlation to rainfall. Rainfall therefore increases the ‘dilution capacity’ potential of the catchment, whereby the water system increases in its ability to receive and remove pollutants disposed in them by human induced land-use activities. It was also found from the study that the strength and association between rainfall and water quality constituents is affected by external, anthropogenic variables which also exert an influence on the quality of water present in the Roodeplaat Catchment Area. This includes additional inputs from the Baviaanspoort, which is located along the Pienaars River. Results from the sample site located on this river displayed no relationship for many of the water quality constituents tested. It has also been highlighted from the study how the landscape has been severely altered by the rapid rate of human induced land use activities in the past decade. Further investigations need to incorporate the influences of natural phenomena, such as rainfall, together with influences exerted from anthropogenic activities. This will provide clearer information on the interdependent factors at play which compromise the dilution capacity potential of the Roodeplaat Catchment Area and subsequently the poor water quality status exhibited at the impoundment. Once such externalities are accounted for, it is recommended that a suitable management plan be conducted for the Roodeplaat Catchment Area that is based on scientific grounding and proactively mitigates the impacts exuded by land-use activities, thereby improving the status of the Roodeplaat impoundment. ii ACKNOWLEDGEMENTS It is with great sincerity and gratitude that I acknowledge the following persons and institutions for their significant contributions to the completion of this research study: Professor J.T. Harmse, my supervisor, for his invaluable contributions, provisions made and time spent on the review of my study. His manner of kindness, words of wisdom and open-door policy has been an incredible support system, not only through this process, but throughout my studies at the university. To all the staff members at the department who continuously give of themselves to the students and have made my time at the university a thoroughly enjoyable experience. The Department of Water Affairs and South African Weather Service for the supplement of raw data used in this study. To my incredible parents and brothers, who have supported me at every turn and encouraged me to fulfil my ambitions. Their unwavering faith and love for me has been such a vital piece of this puzzle. To all my family and friends for their support, I thank you. And finally, to my Heavenly Father, who has guided me through seasons of hardships and seasons of prosperity- who is always with me. Words could not justify my love or gratitude to Him. iii TABLE OF CONTENTS ABSTRACT i ACKNOWLEDGEMENTS iii LIST OF FIGURES vi LIST OF TABLES vii ABBREVIATIONS USED xi 1. INTRODUCTION . 1 2. MOTIVATION FOR STUDY: PROBLEM STATEMENT AND OBJECTIVES 2 3. LITERATURE REVIEW 6 4. DESCRIPTION OF STUDY AREA 15 4.1 Location, Boundaries and Size 17 4.2 The Main Land-Use Activities in the Roodeplaat Dam Catchment Area that Impact on Water Quality 21 4.2.1 Land-use activities along the Pienaars River 23 4.2.2 Land-use activities along the Edendale Spruit. 24 4.2.3 Land-use activities along the Hartebees Spruit 25 4.2.4 Land-Uses Changes in the Roodeplaat Catchment Area. 25 5. WATER QUALITY AND WATER QUALITY CONSTITUENTS IN THE ROODEPLAAT DAM CATCHMENT AREA (2000-2009) 28 5.1 Physical Constituents 29 5.1.1 pH 29 5.1.2 Dissolved Major Solids (DMS) 29 5.2 Chemical Constituents 30 5.2.1 Inorganic Nitrogen (NH4) 30 5.2.2 Phosphates (PO4) 32 5.2.3 Sulphates (SO4) 35 5.2.4 Magnesium (Mg) 35 5.3 Microbial Constituents 36 iv 5.3.1 E- Coli 37 6. DATA COLLECTION AND METHODOLOGY 40 6.1 Data collection and location of sample sites 40 6.2 Shortcomings of Data 42 6.3 Analysis of Data 43 7. RAINFALL OF THE ROODEPLAAT DAM 45 CATCHMENT AREA (2000-2009) 8. RESULTS AND DISCUSSION 46 8.1 Physical Constituents 46 8.1.1 pH 46 8.1.2 Dissolved Major Solids 48 8.2 Chemical Constituents 51 8.2.1 Inorganic Nitrogen 51 8.2.2 Phosphates 55 8.2.3 Sulphates 58 8.2.4 Magnesium 61 8.3 Microbial Constituents 65 8.3.1 E-Coli 65 8.4 Impact of Rainfall on water quality for the Roodeplaat Dam 69 Catchment area (2000-2009) 9. CONCLUSION 72 10. REFERENCE LIST 74 v LIST OF FIGURES Figure 1: Spatial Distribution of Mean Annual Precipitation across Southern Africa. 6 Figure 2: Distribution of Large Impoundments in South Africa. 8 Figure 3: Water Management Areas within South Africa. 15 Figure 4: Overview of the Crocodile (West) Marico Water Management Area. 16 Figure 5: Location of the study area within the Gauteng Province, South Africa. 17 Figure 6: Locality of Study Site. 18 Figure 7: Map of the Three Sub-Catchment Regions within the Roodeplaat Dam Catchment 20 Area. Figure 8: Land-use Activities within the Roodeplaat Catchment Area. 22 Figure 9: Changes in Land-Use Activities from 1997 to 2010 26 Figure 10: Roodeplaat Dam in December 2008. 33 Figure 11: Roodeplaat Dam in January 2009. 33 Figure 12: Fish deaths as a result of toxic cyanobacterial blooms. 34 Figure 13: Location of Sampling Points in Relation to Surrounding Land-use Activities. 41 Figure 14: Location of Sampling Points in Designated Study Area. 41 Figure 15: Location of Weather Station used in Study. 42 Figure 16: Interpolation of Incomplete Data Sets. 44 Figure 17: Results of Rainfall Tracking Over the Study Area (2000-2009). 45 Figure 18: Comparison of Sample Point concentrations of pH. 46 Figure 19: Results of pH and Rainfall Tracking at SP2. 47 Figure 20: Results of pH and Rainfall Tracking at SP4. 48 Figure 21: Results of DMS and Rainfall Tracking at Sample Point 3. 49 Figure 22: Results of DMS and Rainfall Tracking at Sample Point 2. 49 Figure 23: Comparison of Nitrate Concentrations at each of the Study Sample Points. 51 Figure 24: Inorganic Nitrogen and Rainfall Tracking at Sample Point 1.